Technical Field
The present invention generally relates to improving the efficacy of methods of viral transduction of cells. More particularly, the present invention provides methods and materials useful for improving the efficiency of transducing cells, such as human hematopoietic stem cells (HSC), with viruses and/or viral vectors that may be useful for therapeutic indications.
Description of the Related Art
The Food and Drug Administration (FDA) has not yet approved any human gene therapy product for sale. Current gene therapy is experimental and has not proven very successful in clinical trials. Little progress has been made since the first gene therapy clinical trial began in 1990. In 1999, gene therapy suffered a major setback with the death of 18-year-old Jesse Gelsinger. Jesse was participating in a gene therapy trial for ornithine transcarboxylase deficiency (OTCD). He died from multiple organ failures 4 days after starting the treatment. His death is believed to have been triggered by a severe immune response to the adenovirus carrier.
Another major blow came in January 2003, when the FDA placed a temporary halt on all gene therapy trials using retroviral vectors in blood stem cells. FDA took this action after it learned that a second child treated in a French gene therapy trial had developed a leukemia-like condition. Both this child and another who had developed a similar condition in August 2002 had been successfully treated by gene therapy for X-linked severe combined immunodeficiency disease (X-SCID), also known as “bubble baby syndrome.” FDA's Biological Response Modifiers Advisory Committee (BRMAC) met at the end of February 2003 to discuss possible measures that could allow a number of retroviral gene therapy trials for treatment of life-threatening diseases to proceed with appropriate safeguards. In April of 2003, the FDA eased the ban on gene therapy trials using retroviral vectors in blood stem cells.
Recently, however, several groups have led moderately successful gene therapy trials in combating several diseases. In, 2008, UK researchers from the UCL Institute of Ophthalmology and Moorfields Eye Hospital NIHR Biomedical Research Centre announced a successful gene therapy clinical trial for treatment of Leber's congenital amaurosis, a type of inherited blindness. The results showed that the experimental treatment is safe and can improve sight (Maguire et al., N Engl J. Med. 358(21):2240 (2008)).
In 2011, Neurologix, Inc. announced positive results in a Phase 2 trial of its investigational gene therapy for advanced Parkinson's disease (PD), NLX-P101. Study participants who received NLX-P101 experienced statistically significant and clinically meaningful improvements in off-medication motor scores compared to control subjects who received sham surgery. In the trial, this benefit was seen at one month and continued virtually unchanged throughout the six month blinded study period. The results also demonstrated a positive safety profile for NLX-P101, with no serious adverse events related to the gene therapy or surgical procedure reported. Patients enrolled in the trial had moderate to advanced PD and were not adequately responsive to current therapies.
In 2009, a French group of scientists reported using hematopoietic stem cell mediated gene therapy to successfully treat X-linked adrenoleukodystrophy (ALD). Autologous stem cells were removed from the patients, genetically corrected ex vivo and then re-infused into the patients after they had received myeloablative treatment. Over a span of 24 to 30 months of follow-up, polyclonal reconstitution, with 9 to 14% of granulocytes, monocytes, and T and B lymphocytes expressing the ALD protein was detected. These results strongly suggest that hematopoietic stem cells were transduced in the patients. Beginning 14 to 16 months after infusion of the genetically corrected cells, progressive cerebral demyelination in the two patients stopped.
Recent progress in the field of gene therapy has raised the hope that patients afflicted with hemoglobinopathies such as β-thalassemia and sickle cell anemia will benefit from novel therapeutic approaches. Transplantation of hematopoietic cells (HCs) modified with lentiviral vectors carrying the β-globin gene has resulted in long-term correction of several mouse models of hemoglobin disorders Imren et al., Proc Natl Acad Sci USA. 2002; 99(22):14380-14385; Malik et al., Ann NY Acad. Sci. 2005; 1054:238-249; May et al., Nature. 2000; 406(6791):82-86; Pawliuk et al., Science. 2001; 294(5550): 2368-2371), but in contrast, has led to transfusion independence in only one β-thalassemic patient (Cavazzana-Calvo et al., Nature. 2010; 467(7313):318-322).
Although the main advantages of infusing genetically modified autologous cells are to avoid the risks of GVHD and immunosuppressive pretransplant conditioning as well as to address the lack of compatible donors, current therapy faces at least three substantive caveats: the requirement for toxic myeloablation (Dunbar et al., Hum Gene Ther. 1998; 9(17):2629-2640); current gene transfer methods are unable to transduce more than a fraction of hematopoietic stem cells (HSCs) (Santoni de Sio and Naldini, Methods Mol. Biol. 2009; 506:59-70); and various in vivo selection strategies available suffer from suboptimal efficacy and safety (Beard et al., J Clin Invest. 2010; 120(7):2345-2354; Cornetta et al., Cancer Gene Ther. 2006; 13(9):886-895; Milsom et al., Cancer Res. 2008; 68(15): 6171-6180). For example, in disorders amenable to hematopoietic stem cell therapy, e.g., sickle cell disease, β-thalassemia, adrenoleukodystrophy, and adrenomyeloneuropathy, limitations include, but are not limited to, inefficient transduction of hematopoietic stem or progenitor cells, the requirement for toxic myelosuppressive or myeloablative therapy, and a lack of optimal methods for in vivo selection of transduced cells.
Accordingly, there is a need in the art for improved methods of gene therapy and, in particular, for the treatment or prevention of hematopoietic disorders. The present invention offers solutions to these and other problems that plague the art.